The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Fuel injector tip seals are commonly provided at the interface between the fuel injector and an aperture in the head of the engine through which the fuel injector extends for injecting fuel directly into the cylinders of the engine. The fuel injector tip seals are subjected to compression temperatures and pressure which create design concerns relating to the life span of the seals.
The present disclosure provides fuel injector tip seal designs that are intended to improve the durability of the tip seal. According to one aspect of the present disclosure, a tip seal is provided including a ring-shaped body formed of polytetrafluoroethylene that includes between 10 and 35 percent carbon. The carbon filled PTFE provides improved surface finish and deformation resistance and improved thermal conduction and reduced thermal expansion, as compared to current injector tip seals which use approximately 20 percent glass bead filled PTFE or 25 percent glass fiber filled PTFE.
According to another aspect of the present disclosure, the fuel injector assembly is provided with an elongated injector body having a fuel passage extending therethrough and terminating at a tip thereof. The injector body includes a recessed groove in an outer diameter thereof having a first radially extending end wall and a second radially extending end wall spaced from the first end wall by a first distance. The first end wall is disposed in closer proximity to the tip than the second end wall and a continuously sloped axially extending recessed base wall surface extends from the first end wall to the second end wall such that a first end of the continuously sloped axially extending surface adjacent to the first wall has a smaller diameter than a second end of said continuously sloped axially extending surface adjacent to said second end wall. A ring-shaped seal body is disposed in the recessed groove. The slope of the base wall of the groove creates more pressure to the outside diameter face of the seal body when pressure is applied at the tip. The groove diameter is provided so that an increased axial clearance is provided between the end walls of the groove and the end walls of the ring-shaped seal body to allow for PTFE expansion and deformation at increased temperatures.
According to a further aspect of the present disclosure, a fuel injector tip seal is provided including a seal body having an uninstalled flat disk-shape with a pair of sidewalls having an aperture centrally located therein and a radial dimension extending radially from said central aperture to an outer periphery. The seal body is inserted in a recessed groove in the injector body with the pair of sidewalls being flipped so as to be disposed such that the radial dimension of the pair of sidewalls extend axially relative to the elongated injector body. A cone-shaped assembly tool can be utilized to assist in sliding the seal body onto the fuel injector body and into the recessed groove. The disk-shaped seal body provides a significant reduction in cost for both material and labor by eliminating the machining that is required for conventional seal designs.
Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.